1. FIELD OF INVENTION
The present invention relates broadly to the binding of ski boots to skis and more particularly to the binding of ski boots to cross country skis. With still more particularity, the present invention relates to restraint of unwanted motions of the heel of a cross country ski boot with respect to a cross country ski.
2. PRIOR ART
With downhill skis, it is desirable that the ski boot be firmly and substantially immoveably attached to the ski boot at its toe and at its heel, so that the skier may substantially control the orientation skis as he travels downhill under the influence of gravity. The bindings securing the boot to the ski for downhill skiing should release in the event of dangerous levels of stress applied to the ankle or legs of the skier, and the art of such ski bindings is well advanced so that the danger of injury to the skier is reduced in the event of spills and the like. The use of cross country and mountaineer skis contrasts with the use of downhill skis, in that the heel of the ski boot must be free to move vertically with respect to the ski, so that the skier may stride forward to propel the skis and the skier along the surface of the snow. Such forward striding requires that the heel be free to move vertically with respect to the ski. Cross country ski boots and the like are therefore typically relatively flexible in contrast to the substantially rigid downhill ski boots, and are fastened firmly to the ski only at their toes. In the course of propelling himself along the snow upon the skis, the cross country skier must alternately place substantially his entire weight upon the approximate center of the ski, the bottom of which is adapted to provide the necessary friction. In this aspect of the use of cross country skis, it is extremely desirable that the foot be aligned generally axially with the ski.
Heretofore, no effective apparatus has been provided to effectively prevent the tendency toward rotation of the ski boot heel laterally in respect to the ski. This has resulted in considerable difficulty for the skier to keep his foot aligned over the ski to provide the necessary traction for forward motion and to easily keep the skis aligned in a parallel forward orientation to facilitate his travel along the surface of the snow. With the present bindings, further difficulty arises when the cross country skier coasts downhill in that the skier can exercise less than desirable control over the skis to control either his downhill velocity or his direction of downhill motion. To partially obviate the aforesaid problems some bindings for the heel of cross country ski boots have provided for the manual selection between substantially full restraint of the heel in both the lateral and vertical directions and substantially total lack of such restraint. With this approach, the skier must frequently successively manually release and secure the heel of his ski boots to the skis, resulting in much difficulty, and often exasperation, on the part of the skier. Further, such an approach is inherently dangerous, since the skier may inadvertently leave the heel of his boot unattached when it should be attached to provide needed control, and vice versa.
Another approach to the problem of providing free vertical movement of the heel while restraining its lateral movement has involved the use of elastic or spring tensioned cables engaging the heel to the ski. This approach, however, does not provide for completely unimpeded vertical movement of the heel, nor does it substantially prevent the undesired lateral movement.